The present invention relates to a touch sensitive electronic musical or sound generating instrument. Electronic musical instruments such as keyboard type instruments have long been known for generating musical sounds corresponding to actuation of one or more keys on the keyboard. The desired note or sound corresponds to depression of a particular key and the loudness or other parameter of the sound corresponds in some fashion to how hard the particular key or keys were depressed.
In instruments known as polyphonic type instruments, several sounds can be created simultaneously. With polyphonic keyboard type instruments, it is desirable to detect how hard each push button or key was actuated or depressed in order to generate a musical sound or tone having a specified volume level or other parameter corresponding to how hard the respective key or botton was depressed.
In one approach, the prior art provides two switches per button or key, which are sequenced such that by measuring the time between switch closures, the button velocity can be determined. This approach requires accurate physical switch sequencing and fast scanning times. A second approach in the prior art is where each button or key is provided with an analog pressure sensor. The key or button that is struck measures pressure. Continuous pressure can also be used to modulate the desired sound. This second approach requires analog multiplexing equipment and expensive push buttons. A further problem with the second approach is the wear and tear on the push buttons.
A third approach is where a vibration sensor is provided for each key or button. In this third approach, the button directly strikes a vibration sensor. As with the second approach described above, this requires expensive buttons, and an analog multiplexer. Also, crosstalk between buttons can degrade performance.
A fourth approach is in monophonic equipment, where only one sound is played at a time. With only one sound generated at one time, only one button is actually used. The problem with this approach is generation of only one sound (as contrasted with polyphonic equipment) and in addition, crosstalk can be a detrimental factor.